Poly(ethylene/alkylene) terephthalates which crystallize rapidly

Abstract

Terephthalic copolyesters, the diol component of which mainly consists of ethylene glycol units, crystallize more rapidly than pure polyethylene terephthalate and can be moulded in a way comparable to polybutylene terephthalate.

We claim: 
     
       1. A highly crystalline, thermoplastic terephthalic acid copolyester which crystallizes rapidly, said copolyester consisting of a dicarboxylic acid component, at least 90 mol %, based on the dicarboxylic acid component, of said dicarboxylic acid component being condensed terephthalic acid radicals, and 90 and 99.5 mol %, based on the diol component, of said diol component being condensed ethylene glycol radicals and 0.5 to 10 mol %, based on the diol component, thereof being condensed radicals of a member selected from the group consisting of hexane-2,5-diol, 2,2,4-trimethylpentane-1,3-diol, and 2-methylpentane-2,4-diol. 
     
     
       2. The copolyester of claim 1 wherein said member selected from said group is hexane-2,5-diol. 
     
     
       3. The copolyester of claim 1 wherein said member selected from said group is 2,2,4-trimethylpentane-1,3-diol. 
     
     
       4. The copolyester of claim 1 wherein said member selected from said group is 2-methylpentane-2,4 -diol. 
     
     
       5. A process for the production of thermoplastic terephthalic acid copolyesters which crystallize more rapidly than polyethylene terephthalate homopolymer comprising (1) esterifying or transesterifying an acid component consisting of (a) at least 90 mol % of terephthalic acid and dimethyl terephthalic acid ester, and   (b) up to 10 mol % of other aliphatic and aromatic dicarboxylic acids and acid esters with     (2) 1.05 to 2.40 equivalents of a diol component consisting of (a) 90 to 99.5 mol % of ethylene glycol, and   (b) 10 to 0.5 mol % of a codiol selected from the group consisting of hexane-2,5-diol; 2,2,4 trimethyl pentane-1,3-diol; and 2-methyl pentane-2,4-diol at     (3) a temperature of between 150° and 250° C in the presence of esterification or transesterification catalysts, and   (4) polycondensing the initial reaction products at a temperature between 200° and 300° C under reduced pressure in the presence of an esterification catalyst, wherein the codiol is added to the reaction mixture after substantially all of the acid component has been reacted to di(2-hydroxyethyl)ester.     
     
     
       6. The process of claim 5 wherein the codiol is 2-methyl pentane-2,4-diol. 
     
     
       7. The product of the process of claim 5. 
     
     
       8. The product of the process of claim 6. 
     
     
       9. The process of claim 5 wherein the codiol is added to the reaction mixture after formation of a polyethylene terephthalate prepolymer with a degree of polymerization greater than 4 but before the polycondensation step. 
     
     
       10. The process of claim 9 wherein the codiol is 2-methyl pentane-2,4-diol. 
     
     
       11. A highly crystalline, thermoplastic terephthalic acid copolyester which crystallizes rapidly, said copolyester consisting of a dicarboxylic acid component, at least 90 mol %, based on the dicarboxylic acid component, of said dicarboxylic acid component being condensed terephthalic acid radicals, and 90 to 99.5 mol %, based on the diol component, of said diol component being condensed ethylene glycol radicals and 0.5 to 10 mol %, based on the diol component, thereof being condensed radicals of 3-methylpentane-2,4-diol. 
     
     
       12. A process for the production of thermoplastic terephthalic acid copolyesters which crystallize more rapidly than polyethylene terephthalate homopolymer comprising (1) esterifying or transesterifying an acid component consisting of (a) at least 90 mol % of terephthalic acid and dimethyl terephthalic acid ester, and   (b) up to 10 mol % of aliphatic and aromatic dicarboxylic acids and acid esters with     (2) 1.05 to 2.40 equivalents of a diol component consisting of (a) 90 to 99.5 mol % of ethylene glycol, and   (b) 10 to 0.5 mol % of 3 methyl pentane-2,4-diol at     (3) a temperature of between 150° and 250° C in the presence of esterification of transesterification catalysts, and   (4) polycondensing the initial reaction products at a temperature between 200° and 300° C under reduced pressure in the presence of an esterification catalyst, wherein the codiol is added to the reaction mixture after substantially all of the acid component has been reacted to di(2-hydroxyethyl)ester     
     
     
       13. The product of the process of claim 12. 
     
     
       14. The process of claim 12 wherein the codiol is added to the reaction mixture after formation of a polyethylene terephthalate prepolymer with a degree of polymerization greater than 4 but before the polycondensation step.